This invention relates to the monitoring of one or more inputs to develop an audible signal representative of the monitored input or inputs. It has particular application to the monitoring of body conditions, such as heart rate, systolic blood pressure, diastolic blood pressure, and body temperature, to name some examples, although it has broad application to the monitoring of any condition or conditions leading to the generation of a distinguishable audible output that varies in accordance with the monitored condition or conditions. The present invention is directed toward providing a distinguishable audible output that may be easily interpreted by an observer, without the need to visually inspect an instrument panel or to do anything beyond simply listening to the generated audible signal.
There are two principal aspects of the present invention; the first relates to the quantizing of a monitored input to produce an audible signal that varies in a plurality (n) of discrete steps that correspond to a range of variation in value of the monitored input. Thus, for example, if an electrocardiograph signal is monitored to develop an intermediate signal that is representative of the rate at which the heart is beating, that signal is quantized, for example, by use of a voltage to frequency converter having a step function input/output characteristic, to generate an audio signal that varies in a plurality (n) of discrete steps. Accordingly, a technician listening to the audible output signal will detect changes in frequency or amplitude, for example, as the output changes from one level to another, representing a change in the monitored electrocardiograph input. Since the output audible signal varies in step fashion, it is easier for the technician or physician to note a change, than if the output signal were to vary in continuous fashion. Small changes in a continuously varying output signal occurring over a relatively long period of time might not be noticed as any change at all.
A second aspect of the present invention lies in the monitoring of a plurality of different inputs. Again, to use the monitoring of body conditions as an example, if heart rate, systolic blood pressure, pulmonary artery diastolic blood pressure, and body temperature are all monitored, the present invention provides for the development of a distinguishable audible signal in which a plurality of different parameters of that signal each correspond to an individual one of the monitored inputs. Thus, for example, an audio signal may be generated composed of a series of recurring pulses, and the parameters of that signal corresponding to the monitored conditions are as follows:
(a) amplitude of each pulse (corresponding to pulmonary artery diastolic blood pressure), PA0 (b) time duration of each pulse (corresponding to body temperature), PA0 (c) time duration between the onset of successive pulses, i.e., the periodicity (corresponding to heart rate), and PA0 (d) frequency of the signal defining each pulse (systolic blood pressure).
In such a system in which a plurality of different inputs are monitored, by varying an audible output parameter in accordance with the variation of an individual input, the technician or physician is able to continue his tasks and, by simply listening to the output signal, note when one of the monitored conditions changes. There is no need to visually inspect instrumentation, and the user may be easily trained to detect changes in any of the parameters of the audible output signal. In this regard, it should be noted that any one or more of those parameters may be quantized so that it varies in discrete steps corresponding to a range of monitored input variation, as described above.
The invention will be more completely understood by reference to the following detailed description of representative but presently preferred embodiments thereof.